This application will inform the debate on health care policy for persons with severe mental illness. Advocacy groups (including provider organizations) argue that a reformed health care system should not discriminate against persons with severe mental illness. On the other hand, insurers and payers (especially employers) object that it would be ruinously expensive to include persons with severe mental illness in a comprehensive health care program. Meanwhile, many current proposals for health care reform depend on the expansion of health maintenance organizations (HMOs). This study will provide policy makers with useful and timely information about the costs of providing services to severely mentally ill HMO members. The project is the next logical step in a program of research designed to characterize a cohort of persons with schizophrenia or bipolar disorder enrolled in the Northwest Region of Kaiser Permanente. During the first part of this study we identified 250 severely mentally ill HMO members and two sets of Age- and sex-matched controls. We measured the subjects' use of HMO services and their duration of enrollment in the organization over a five year follow-up period. As expected, we found that the severely mentally ill subjects used more services than did the controls. Surprisingly, the severely mentally ill subjects maintained their HMO membership longer than the controls. We now propose to calculate costs of providing HMO services to these subjects. We will also examine the subjects' careers in the HMO as well as their use of public mental health services with the aim of understanding why some (about half) of the severely mentally ill subjects were able to maintain enrollment while others left the organization. A key feature of this study is that the comparisons of severely mentally ill with physically ill subjects as well as the comparisons of "leavers" with "stayers" are based on data from a large, long-standing health maintenance organization of the type expected to figure prominently in a revamped health care system.